This invention relates generally to gas turbine power plants, and more particularly, to a system and method for reducing gas turbine nitric oxide (NOx) emissions without incurring penalties associated with either combustion efficiency or carbon monoxide (CO) emissions.
Pollutant emissions from gas turbine power plants have been of great concern in the past several decades. Stringent regulations have been established to lower these emissions, especially nitric oxides to single digits. One of the solutions currently in use to reduce these NOx emissions employs selective catalytic reactors (SCR)s. Selective catalytic reactors undesirably are expensive, have a large footprint, and present additional concerns regarding ammonia slip.
Combustion with vitiated air is a proven technique for reducing NOx emissions by affecting the NOx kinetic mechanisms, changing the flame structure and lowering the peak flame temperature. Combustion staging has also been shown to reduce NOx emissions in applications including, for example, axial staging, late lean and sequential combustion systems (reheat).
It would be desirable to provide a system and method that further reduces NOx emissions below limits achievable using known techniques, without incurring penalties in terms of combustion efficiency or CO emissions.